Generally, thermoplastic resins can have an excellent balance of physical properties and excellent moldability, and can be a substitute for glass or metal due to their low specific gravity. Accordingly, thermoplastic resins are widely used for various products such as automobile parts, electrical/electronic appliances, and the like.
Recent trends require lower prices, reduced weight, and scaled up sizes of electrical/electronic appliances. Accordingly, products formed of thermoplastic resins are increasingly used for housing materials of deluxe appliances such as LCDs, PDPs, TVs, audio equipment, and the like.
The functionality, performance and appearance of such housing materials are important, and demand for scratch resistance has also increased. At the same time, such products increasingly include complex shapes and/or thin film components. Therefore, moldability of the resins is also an important consideration.
Polycarbonate resin is an engineering plastic having excellent mechanical strength, heat resistance, transparency, weather resistance, flame resistance and the like. Accordingly, polycarbonate resin is used widely for electrical/electronic appliances, automobile parts, building materials and the like. Polycarbonate resin can also be a substitute for glass in applications demanding both transparency and impact resistance such as lens. However, polycarbonate resin has poor scratch resistance.
One method for improving scratch resistance includes applying a hybrid material on a surface of a molded product and hardening the hybrid material using UV radiation. Another method for improving scratch resistance includes coating acrylic resin having excellent scratch resistance or painting urethane resin on a molded product. However, these methods are time consuming due to the additional post-processing steps and also can cause environmental pollution.
Scratch resistance of a polycarbonate having existing excellent physical properties can be improved by mixing acrylic resin such as polymethyl methacrylate having excellent scratch resistance with polycarbonate resin having excellent flame resistance or physical properties such as impact strength. The acrylic resin such as polymethyl methacrylate can have excellent transparency, weather resistance, physical strength, and surface gloss, and can improve scratch resistance.
However, polycarbonate/acrylic resin blends do not have high transparency and coloring properties due to low compatibility and the difference between the refractive indices of the resins. Thus, the use of polycarbonate/acrylic resin blends is limited in housings for electrical/electronic appliances requiring complex shapes and/or a thin film. The use of such blends is further complicated due to the high melting viscosity of polycarbonate.